System of illumination



Jan. 7, 1936. N. 1. PRO'SSER 2,0273118 SYSTEM OF ILLUMINATION Filed Aug. 7, 1931 2 Shets-Sheet 1 Jan. 7, 1936.

N. I. PROSSER 2,027,118 SYSTEM OF ILLUMINATION Filed Aug. 7, 1931 2 Sheets-Sheet 2 Patented .ian. 7, '1936 UNITED STATES PATENT OFFICE 9 Claims.

This invention relates to a system for illuminating gas discharge tubes.

Such tubes are now well-known and are extensively used for advertising and display purposes. They usually include a filling of an inactive gas that can be ionized by impressing a sufllciently high potential difference across the tube, as by the aid of appropriate electrodes. A common form of such tubes is that utilizing a noble monatomic gas, such as neon, argon or helium, or a mixture thereof, at a pressure of the order of from four to twenty millimeters o mercury.

Such tubes can be operated to be brilliantly luminescent at a current consumption of about 20 to 30 milliamperes. Constant current transformers are usually utilized to provide a uniform current to any length of tubing within the limits of the transformer capacity, and up to about 15,000 volts.

Such tubes, to attract more attention, have been flashed, that is, instantaneously and intermittently energized. The attractiveness can be still further enhanced by moving the tube during such intermittent energization, as by mounting it on a disc that can be rotated. When the speed of rotation is sufficient and the periods of energization are short enough, the persistence of vision produces the efl'ect of a large number of tubes simultaneously energized. If a plurality of tubes of different colors are mounted on a common disc, and each flashed so that at times their periods of illumination overlap, and at other times do not, a changeable efiect of great attractiveness is obtained.

It is one of the objects of my invention to provide a simple and efiective system for flashing one or more such tubes, either stationary or rotating.

It is another object of my invention to provide a simple and convenient flasher mechanism for this purpose.

More particularly, the flasher utilized with the tubes is of the thermal type, where alternate heating and cooling of a metal member serves to open and close the energizing circuit. Although such thermostatic control devices are in general well-known, I utilize a novel heating principle that has the advantage of simplicity and inexpensiveness.

Thus I utilize the heat generated adjacent the contacts for operating the metal parts. This can be accomplished by appropriate choice of materials for the contacts, which offer such a resistance to the passage of current as to produce the required heat; or else by arcing the current between contacts and utilizing the heat of the are for this purpose.

My invention possesses many other advantages, and has other objects which may be made 5 more easily apparent from a consideration of several embodiments of my invention. For this purpose I have shown a few forms in the drawings accompanying and forming part of the present specification. I shall now proceed to 1o describe these forms in detail, which illustrate the general principles of my invention; but it. is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of my invention is best defined by the ap- 15 pended claims.

Referring to the drawings:

Figure 1 is a diagram illustrating the mode 01' operation of my invention;

Figs. 2 and 3 are diagrams showing various 20 applications of my invention to luminous tube systems;

Fig. 4 is a diagram of another form of my invention;

Fig. 5 is an enlarged fragmentary view of a 26 modified form of contacts used with my invention; and

Fig. 6 is a diagram of still another form of the invention.

In Fig. 1 there is disclosed a luminous tube ll 30 of indefinite length, having conductors l2 and I3 for impressing an energizing potential across the column of gas in the tube. Internal electrodes l4, I5, are indicated. The energizing potential is shown as supplied by the secondary or 35 high potential coil iii of a constant current transformer IT. The primary coil 18 is shown as connected to commercial mains I9 of low potential.

I provide a flasher mechanism which period- 40 ically serves to deenergize the tube Ii, as by short circuiting it. Since transformer i1 is of the constant current type, such short circuiting does not harmfully raise the current flow through the transformer coils. This short cir- 45 cuiting is accomplished by the aid of a pair of contact points 20, 2!.

Contact point 20 is stationery and is connected to one side of the coil I 6. The other contact point 2| is movably mounted on a 'bi- 50 metallic strip 22, which is so arranged as to flex downwardly when its temperature increases materially above room temperature. This strip is fastened at that end remote from the contact 2!, on a block 23, and a post 24 connects 55 this end of the strip to the other side of coil it.

It is apparent that when current flows between contacts 20, 2|, the resistance of the path including strip 22, and these contacts, is so much less than the resistance of tube II that the potential drop across this shunt circuit is insufficient to light tube Therefore all of the current flows through this shunt circuit and the tube stays .dark. As soon as the contacts separate to an extent such that the potential .causes this strip to be heated and therefore flex downwardly, breamng the shunt circuit and causing tube H to luminesce. Since current then no longer flows through the contacts, there is no creation of heat, and the bimetallic strip after a short interval, assumes its normal cold position. The shunt circuit is then again energized, and the cycle is repeated.

I find it advantageous, however, to utilize the heat of an arc across the contacts 20, 2| for heating the bimetallic element 22. For this purpose, the normal unflexed position of the strip 22 positions the contact 2| merely within arcing distance, and not in actual contact with contact 20. Contact 2| is, of course, made of material that can withstand arcing. The spacing of the contacts 20, 2| is such that the arcing resistance is much less than the tube resistance while the tube is deenergized and accordingly an are forms between the contacts and no current flows through the tube l|.

As soon as suflicient heat is transferred to member 22, it flexes downwardly and draws out the arc. The are resistance then increases. When it reaches the position 26 the arc resistance may be as great as the normal resistance of tube II, but the voltage developed thereby is insuflicient to strike the tube. When it is sufficient to produce a potential difference to strike the tube II, this tube is energized and robs the arc of current. This condition is represented by the dotted position 25 of the member 22. The tube voltage then decreases and current passes through it to the exclusion of the arc.

Now the member 22 begins to lose heat by radiation, becaue the arc is extinguished. In losing heat, it starts to return to the former position. Since it is necessary for the contacts 20, 2| to approach closer to strike the are after it is once extinguished, there being no ionized air to support the arc, the arc does not again become active until the member 22 returns to the full line position, whenthe cycle is repeated.

This mode of intermittent operation can be applied to a plurality of tubes in series, each tube being shunted by its own flasher mechanism. Such a system is illustrated in Fig. 2.

Here the transformer 21 of the constant current type supplies all of the tubes 28 to 32 inclusive. Each tube is independently controlled by its flasher, such as 33, which shunts the tube.

For successful operation, the tubes should be long enough so that the striking voltage will correspond to an appreciable separation of the flasher contacts, say at least one-thirty-second of an inch.

A plurality of tubes could also be arranged in parallel, and still utilize the principle of the invention. This is illustrated in Fig. 3. In this case, the constant current transformer 34 can supply a plurality of circuits in parallel. Since in the tube circuits are similar, but one will be specifically detailed. Each tube circuit includes a tube 35 and a flasher device 36 in series with it. In this case, since the tube, resistances depend upon a number of factors such as the com- 15 position and pressure of the gas, the length of the tube, the construction of the electrodes, and the amount of current passing through the tube, these resistances are not the same for any of the tubes. Consequently, an arc will form at 20 that flasher mechanism which is in the circuit of least resistance, and all of the current will flow through the are between the contacts and the associated tube in series. As the arc heats the bimetallic strip, the strip flexes and theair gap lengthens. The are continues to act until the combined series resistance of the arc and tube exceeds the combined air gap and tube resistance of another circuit. By arranging the switches to cool slowly, as by providing :u) appropriate heat insulation, the tubes can be illuminated one after another in the group. If the cooling is so slow that none of the switches have returned to normal position by the time each tube has been illuminated, an auxiliary tube 31 can be connected directly across the transformer 34, said tube having a higher resistance than any of the parallel circuits, but within the scope of operation of the transformer 34. This tube will light during the interval until at least one of the switches returns to normal. This tube is thus a safety device to prevent any unusual high voltages, and can also be used as an additional flashing device.

The bimetallic bar 22 is preferably made by 45 attaching a brass strip to a relatively inexpansible strip, so that when heated, the brass strip only elongates and produces the flexure. This bimetallic element can be controlled in a practicable manner as disclosed in Fig. 4. In .in this case the bimetallic element 38 has an inverse. bend something like an 8. One end is rigidly fastened to a block 39. This block carries the post 40 for connecting it to one terminal of the secondary coil 4| of the transas former 42. The other end of the strip 38 engages a notch 43 in an adjustable spring socket 44. This socket is formed of a U spring, one leg being rigidly fastened to a block 45, and the other leg carrying the notch 43. A screw 46 m can be used to urge this leg outwardly and thereby to adjust the free position of the strip 38.

The non-expansible side of this strip is at the top in this form. It carries a contact 41 'which cooperates with a stationary contact post 48. G5 The normal spacing of these contacts can be adjustedby providing a block 49 in which post 48 is threaded. Further adjustment of the position of strip 38 is provided. by the aid of a finger or stop 50 supported on block 39 and 70 urged downwardly to engage the strip 38 beyond the convex left hand portion thereof. Adjustment of finger or stop 50 is provided by a screw 5| engaging the finger.

The arrangement is such that under normal 75 temperature conditions, the strip 38 is in the full line position; the contact 41 placed on the concave portion of the strip and closer to notch 43; and it is slightly above a line drawn from the one end of the strip to the other. The members and 44 are so adjusted that this position is attained, and post 48 is adjusted for providing the desired air gap between it and contact 41. The air gap between members 41 and 48 is included in a series circuit with a discharge tube 52. The entire tube circuit can thusbetraced as follows: coil 4|, post 48, strip 38, contact 41, post 48, tube 52, back to coil 4|.

With an are formed between these contacts, the tube 52 is illuminated. As heat accumulates due to the arc, the lower brass portion of strip 38 expands and the concave part upon which contact 41 is supported, lowers toward a position shown by the dotted lines 53. When the contact 41 moves far enough to carry it to or just below the line joining the ends of the strip 38, it snaps through the center. Appropriate stopping means can be provided for the strip.

For example, an adjustable post can cooperate with a lower contact 54, and can also serve to control another circuit, in a manner to be hereinafter explained.

The resilient anchor 44 permits the member 38 to snap over center. It is apparent that the stop 50 and this anchor 44 cooperate to define the normal configuration of the strip; and this configuration can be varied by appropriate adjustment of these two elements. The post 48 can then be arfiusted to provide the proper arcing distance. The snap over action when suflicient heat accumulates is pronounced and rapid, and causes the air gap between contacts 41, 48 to be so great that current flows by preference through a path alternative to the tube 52, as will be now described. The back contact 54 as before stated, cooperates witth the post 55 to limit the backward movement. This back contact rests firmly against the post 55 and canbe made from good contact metal such as tungsten.

These back contacts can control an alternative circuit from transformer coil 4|, to strip 38, contacts 54, 55, a tube 58, back to the other side of coil 4|. Since the contact 54 rests securely against post 55, there is no material evolution of heat, and the strip 38 loses heat by radiation when these contacts are in engagement. As the strip tends to move away from post 55, it is opposed by a force due to the resilience of member 44. This member acts to keep the right hand portion of strip 38 bent downward, toward post 55. However, upon sufficient contraction of the brass part of strip 38, the resilient force of member 44 is overcome and there is a rapid snap over action to the full line position of Fig. 4. The cycle is then repeated. By proper adjustment of the parts, very little movement is required of contact 41 before it snaps over; and correspondingly, there is no perceptible movement of contact 54 from post 55 until the snap over action takes place to the full line position. Accordingly, there is no danger of producing any material heat when the back contacts are active, since no arc forms at these contacts.

It is apparent that the potential difference delivered by coil 4| must be suflicient to provide the arcing voltage between contacts 41, 48, as

well as the striking voltage of tube 52. The system of Fig. 4 can be used to energize the two tubes 52 and 55 alternately; although either may be removed from the circuit if desired. The time interval of flashing is controlled by the compression at notch 43, the shape of strip 38,

"and the distance of travel between the contact 54 and post 55.

The adjustable stop 50, which helps to define the shape of strip 38, is an important element. In lieu of this form of stop, the form shown in Fig. 5 can be used. In this case, an insulation point 51 is inserted into the post 48 and acts to in space the end of the post from the cooperating arcing contact 41. In order to withstand the heat generated by the are as well as the pounding of the contact 41, proper insulation material should be chosen for this point 51. A quartz l5 tip has been found practical, which can be soldered in place and can project about onesixty-fourth of an inch beyond the end of post 48.

A definite stop limiting the spacing of contacts 41, 48 is important, for it ensures that .o the strip 38 will always return, when cool, to the same configuration and with precisely the same air gap separation of contacts 41, 48. Thus any objectionable flicker due to lengthening of the gap is prevented.

The tubes shown in Fig. 4 can be either stationary or rotating and of different colors- A more complex system, involving three tubes, is illustrated in Fig. 6. In this case, the secondary coil 58 of a high voltage constant current trans- :Z') former 59 is shown as being divided into two sections, as by a ground connection 60. In a well designed transformer, either of these sections could be short circuited without interfering with the operation of the other section.

The right hand section of coil 58 is arranged to flash a stationary tube 6| that may be used to form stationary letters or characters, alternately with a revolving tube 62. This flashing function is accomplished by a mechanism such 4' as described in Fig. 4, having the bimetallic strip 64, arcing contacts 65, and back contacts 66. The circuits for this part of the system can be traced as follows: from the right hand end of the right hand half of coil 58, to strip 64,-

where the current finds alternative paths; either through front contacts 65, connection 61, tube 62, and collector ring 68, or if the strip 64 is heated to make back contacts active, then through back contacts 65, and tube 5|. At 7/) ground 69 these alternative paths recombine, and continue through ground 6|) to the other side of the coil section.

It is apparent that tubes 62 and 6| will be alternatively energized by the alternate operation of the front contacts 85 and the back contacts 66.

The third tube 10 is also shown as rotating, but is intended to be energized by the left hand portion of coil 58. The flashing of this tube is m accomplished by a flasher mechanism 1| having front contacts 12 and rear contacts 13. When the front contacts 12 are active, the left hand section of coil 58 is short circuited. This short circuit can be traced as follows: from the left hand end of the left hand portion of coil 58, to device 1|, front contacts 12, connection 14 to the center connection of coil 58. When the back contacts 13 are active, the revolving tube 10 is illuminated, through the following circuit: from 70 the left hand end of the left hand portion of coil 58, to device 1|, back contacts 13, tube 10, collector ring 68, and grounds 59, 60 to the center connection of coil 58.

The tubes 62, 10 may be of contrasting colors,

and each may have different colors along its length. They may be rotated on a common support. In such case, the periods of actuation of devices 63, H can be such as to be unequal,

5 whereby overlapping of the tube energization can be secured with attendant brilliant displays.

I claim:

1. In a current controlling device, a bimetallic strip, a stationary support for one end of the strip, a resilient anchor for the other end of the strip and arranged to hold the strip resiliently in a reverse bend and to limit any displacement of said other end to a substantially l5 endwise movement, and means whereby said strip can be heated.

2. In a current controlling device, a bimetallic strip, a stationary support for one end of the strip, a resilient anchor for the other end of the strip and arranged to hold the strip resiliently in a reverse bend and to limit any displacement of said other end to a substantially endwise movement, means whereby said strip can be heated, and means whereby the configuration of the strip can be adjusted so that it returns to that configuration substantially exactly when it returns to its cool condition.

3. In a current controlling device, a bimetallic strip, a stationary support for one end of the strip, a resilient anchor for the other end of the strip to hold it in a bent form and to limit any displacement of said other end to a substantially endwise movement, a current carrying part carried by the strip, and a stationary our- 85 rent carrying part cooperating therewith to produce heat by the passage of current between them, whereby the strip snaps over to interrupt the current. a 4. In a flasher device, a stationary contact, a

40 movable contact, a temperature responsive support for the movable contact and having one end rigidly anchored and the opposite end resiliently anchored to restrain any movement to an endwise direction, and means whereby current 45 passing between the contacts generates heat to cause the support to separate .the contacts for interrupting the current flow, said support upon such separation, cooling after a period to return the contacts to current flowing position.

50 5. In a flasher device, a thermostatic strip having a pair of positions corresponding to low and high temperatures of the strip and having one end rigidly anchored and the opposite end resiliently anchored to restrain any movement to an endwise direction, and a pair of contacts operated. thereby, the current passing through said contacts during the low temperature position acting to generate heat to throw the strip to the high temperature position, said high tem- 50 perature position being such that no current can then flow, permitting the strip to cool and to return to its low temperature position for repeating the cycle.

6. In a flasher device, a thermostatic strip confined at one end to a stationary support and restrained at the other end to an endwise move- 5 ment and capable of snapping from one stable position to another, corresponding respectively to a low and to a high temperature of the strip, and a pair of contacts operated by the strip, to be in current passing relationship during the 10 position corresponding to low temperature, the current passing acting to generate heat to throw the strip to the high temperature open circulating position, where the strip can cool to return to the closed circuiting position for repeating the 15 cycle.

7. In a flasher device, a stationary contact, a movable contact, a temperature responsive support for the movable contact and having one end rigidly anchored and the opposite end resiliently 20 anchored to restrain any movement to an endwise direction, means for spacing the contacts within arcing distance for the passage of current between them and for heating the support, so as to cause it ultimately to separate the con- 26 tacts beyond arcing distance to interrupt the current flow, said support upon such, separation, cooling after a period to return the contacts to current flowing position.

8. In a flasher device, a thermostatic strip 30 having a pair of positions corresponding to low and high temperatures of the strip and having one end rigidly anchored and the opposite end resiliently anchored to restrain any movement to an endwise direction, and a pair of contacts operated thereby, to cause them to approach to arcing position for the passage of current, and to separate them beyond arcing distance, said contacts during the low temperature position acting to generate heat by said arcing to throw the strip to the high temperature position, said high temperature position being such that no current'can flow, thereby permitting the strip to cool and to return to its low temperature position for repeating the cycle.

9. In a flasher device, a thermostatic strip confined at one end to a stationary support and restrained at the other end to an endwise movement and capable of snapping from one stable position to another, corresponding respectively to a low and to a high temperature of the strip, and a pair of contacts operated by the strip, to be in arcing relationship during the position corresponding to low temperature, the current thus passing through the contacts acting to generate heat to throw the strip to the high temperature position beyond arcing distance where the strip can cool to return to arcing position for repeating the cycle.

NORMAN I. PROSSER. 

